Snowthrowers, also known as snowblowers, are machines configured for snow removal. Common embodiments of snowthrowers include walk-behind models designed to be manually pushed by an operator (with or without powered assistance to wheels and/or tracks/treads) and those designed for use as part of or an accessory to an-operator driven riding tractor. The snow-throwing mechanism most commonly includes a “single-stage” or “two-stage” configuration. Single-stage snowthrowers typically use a single impeller (e.g., including a plurality of paddles and/or augers) that both moves snow into a receiving region and dispels it out through a directional discharge passage. Two-stage snowthrowers typically use two structures, with a first auger rotating to break up and move snow to a receiving region where a second impeller (e.g., including one or more paddles) expels the snow through a directional discharge passage. Sometimes, single-stage machines are referred to as “snowthrowers,” while two-stage machines are called “snowblowers;” however, the present application uses the terms interchangeably to refer to “single-stage” or “two-stage” configurations. The differences between them are not generally germane to embodiments of the innovative structure disclosed herein.
Both walk-behind and tractor/driven snowthrowers include a receiving region configured as a box-like housing—generally open to the front and bottom but generally enclosed on the top, rear, and lateral sides—where the first (or only) snow-engaging structure rotates to move the snow either directly to a discharge chute (in a single-stage device) or to an impeller/blower housing (in a two-stage device). The lower edges of the lateral sides ride along or near to the ground during operation. This creates a problem when operating the device on uneven surfaces. For example, when operating the device on a sidewalk or driveway, there are often cracks, holes, off-set edges (e.g., between paver units), or other surface irregularities that interfere with smooth operation. For example, when the surface is covered by snow, it is common for the leading edges of the lateral housing sides to collide with the edge of a sidewalk paver panel that is raised up relative to its neighbor (e.g., by weathering, cracking, an underlying tree root) with sufficient force to abruptly stop forward progress of the device. This collision can damage the housing, and may inconvenience or even injure the operator. Even if the uneven surface is not sufficiently offset to stop the device's forward progress, the device and/or the surface can be damaged.
Existing snowthrower devices may include skid plates or skid shoes. However, these are typically designed only to provide for height adjustment of the housing, and to accommodate very slightly irregular surfaces. FIG. 1A illustrates a typical prior art skid shoe 100, including a mounting flange 102 extending perpendicularly upward from a runner 104. The runner 104 includes a single leading lower face 104a and a single trailing lower face 104b, each of which is oriented at an angle well-exceeding 45° relative to a plane defined by a central runner face 104c. This steep-faced construction provides for rough, jarring navigation across offset sidewalk panels and other uneven surfaces. Typical skid shoes of this and other configurations do not exceed about 4-6 inches in total length and have no more than a single leading face and a single trailing face. The leading end and trailing end of the runner of even the best the prior art skids are squared off, which can lead to them getting caught and/or hung up in, for example, chain-link fencing along the side of a sidewalk or driveway being cleared of snow.
As such, there has long been a need for improved snowthrower skid shoes. A variety of designs have been introduced over the past several decades, but each of them suffers from one or more shortcomings as highlighted above, or otherwise.
It may therefore be desirable to provide a snowthrower skid design that provides for smoothed navigation across uneven and even broken or jagged surface transitions, and that also provides a durable structure that will protect and preserve a snowthrower to which it is mounted as well as the surfaces on which it is used, together with adjacent structures.